a97adc51f9
Resolves: RHEL-215674 Resolves: RHEL-215675 Resolves: RHEL-215676 Resolves: RHEL-215677 Resolves: RHEL-215678 Resolves: RHEL-215679 Resolves: RHEL-215680 Assisted-by: Ymir
54 lines
1.9 KiB
Diff
54 lines
1.9 KiB
Diff
From 363cb74e6b68bdf507ba6070620df9d77208254a Mon Sep 17 00:00:00 2001
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From: Jakub Jelen <jjelen@redhat.com>
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Date: Thu, 26 Mar 2026 16:32:24 +0100
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Subject: [PATCH] CVE-2026-59845 socket: Properly check fork() return code
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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During execution of proxy command, when fork() fails, its return value
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is stored in pid and when the parent process attempts to kill it,
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it sends the kill signal to all processes the calling application has
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access to (except for init).
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This caused nard to debug issues when the system under the load was hitting
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fork failures, which resulted in killing of all the system processes
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(of given user).
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Reported and first patch iteration provided by: Halil Oktay (oblivionsage).
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This code missing fork return value check is in libssh since 2010
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(f31a14b7932ef4cc165ddd8f1f1a5b23eb21beb3), but this issue is exploitable only
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since libssh 0.9.0 as previously there was no implementation of killing
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ProxyCommand children.
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Signed-off-by: Jakub Jelen <jjelen@redhat.com>
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Reviewed-by: Pavol Žáčik <pzacik@redhat.com>
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---
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src/socket.c | 12 +++++++++++-
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1 file changed, 11 insertions(+), 1 deletion(-)
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diff --git a/src/socket.c b/src/socket.c
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index f470bb28..84777058 100644
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--- a/src/socket.c
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+++ b/src/socket.c
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@@ -918,7 +918,17 @@ ssh_socket_connect_proxycommand(ssh_socket s, const char *command)
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pid = fork();
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if (pid == 0) {
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ssh_execute_command(command, pair[0], pair[0]);
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- /* Does not return */
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+ /* child: Does not return */
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+ }
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+ /* parent */
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+ if (pid == -1) {
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+ close(pair[0]);
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+ close(pair[1]);
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+ ssh_set_error(s->session,
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+ SSH_FATAL,
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+ "fork failed: %s",
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+ strerror(errno));
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+ return SSH_ERROR;
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}
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s->proxy_pid = pid;
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close(pair[0]);
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